Apparatus for sucking up and lifting the uppermost sheet material from a stack of such sheet materials

ABSTRACT

A sheet material is sucked at one end and at an intermediate portion between the central portion and the other end thereof, wherein said one end of the sheet material is lifted initially while the sheet material is pressed downwardly at a portion between the sucked portions to cause the sheet material to have a bend between the sucked portions.

United States Patent [191 Shindo [451 July 30, 1974 1 1 APPARATUS FOR SUCKING UP AND LIFTING THE UPPERMOST SHEET MATERIAL FROM A STACK OF SUCH SHEET MATERIALS [75] Inventor: Masashi Shindo, Saitama-ken, Japan [73] Assignee: Pilot Man-Nen Hitsu Kabushiki Kaisha, Tokyo, Japan {22 Filed: Feb. 9, 1973 211 Appl.No.:330,975

[30] Foreign Application Priority Data July 10, 1972 Japan 47-068802 [52] U.S. Cl 271/106, 214/1 BT,214/8,5 D, 294/65 [51] Int. Cl..... B65g 59/04 [58] Field of Search 214/1 BT, 8.5 D; 294/64 R, 294/65; 271/91, 100,106

[56] References Cited UNITED STATES PATENTS 3,322,301 5/1967 Bliss 271/106 X 3.411.640 11/1968 Wallis 214/1 BT X 3,673,759 7/1972 Ayrcs 271/)1 X Primary Examiner-Robert J. Spar Assistant I;'.\'aminvr-George F. Abraham Attorney, Agent, or l"irmE1iot S. Gerber [57] ABSTRACT A sheet material is sucked at one end and at an intermediate portion between the central portion and the other end thereof, wherein said one end of the sheet material is lifted initially while the sheet material is pressed downwardly at a portion between the sucked portions to cause the sheet material to have a bend between the sucked portions.

3 Claims, 8 Drawing Figures APPARATUS FOR SUCKING UP AND LIFTING THE UPPERMOST SHEET MATERIAL FROM A STACK OF SUCH SHEET MATERIALS The present invention relates to method and apparatus for sucking up and lifting the uppermost one of stacked sheet materials and transferring the lifted sheet material to another predetermined place.

In the field of transferring thin sheet materials, such as thin plastic sheets, one after another from a stack of the sheet materials to another predetermined place, there has been known a method in which the uppermost one of stacked sheet materials is subjected to suction force so that the uppermost sheet material is peeled off the other sheet materials and then transferred. Usually, this method is carried out by simultaneously lowering a plurality of suction means at the bottom ends of hollow rods into contact with the uppermost one of stacked sheet materials. Because of the pressure applied to the stacked sheet materials such as by the weight of the suction means, the sheet materials tend to be adhered to each other.

If the uppermost one of such adhered stacked sheet materials is subjected to suction force a plurality of suction means and if the latter and simultaneously lifted up, there takes place a tendency in which the second sheet or the second and third sheet materials are lifted together with the uppermost sheet material due to vacuum pressure. The nearer to the central area of the sheet material are the points on the sheet material at which the suction means contact the same, the greater the tendency.

Several methods and apparatuses have heretofore been proposed in order to eliminate the above difficulty, but all have many shortcomings and fail to provide satisfactory, quick and reliable peeling and transferring operations which have been demanded long time.

It is an object of the present invention to provide a method of quickly and reliably peeling and transferring sheet materials one after another from the top of a stack of such sheet materials and an apparatus for performing the method.

It is another object of the present invention. to provide a method of quickly and reliably peeling and transferring uppermost sheet material from a stack of such sheet materials without causing a second sheet material of the stack to be scratched and an apparatus for performing the method.

It is further object of the present invention to provide an apparatus for peeling and transferring sheet materials from a stack of such sheet materials which has a simplified construction and is inexpensive.

According to one aspect of the present invention, there is provided a method of sucking up and lifting the uppermost sheet material from a stack of such sheet materials and transferring the lifted sheet material to another predetermined place, wherein the top surface of the uppermost sheet material is subjected to suction force at one end thereof and at an intermediate portion between the central portion and the other end of said sheet material; thereafter said one end of said sheet material is lifted while said sheet material is pressed downwardly at a portion between the sucked portions of the sheet material to cause the sheet material to have a bend between the sucked portions so that the sheet material is peeled off lower sheet materials; then the sucked portion of the uppermost sheet material between the other end and the central portion is lifted to separate the uppermost sheet material from the lower ones; and finally the separated sheet material is moved upwardly.

According to another aspect of the present invention, there is provided an apparatus for sucking up the uppermost one of a plurality of stacked sheet materials comprising at least first and second suction means each provided at the lower end thereof with a suction member, said first suction means being disposed above one end of the stacked sheet materials while said second suction means is disposed above the intermediate portion between the other end of the stacked sheet materials and the central portion of the stack, at least one pressure means for applying pressure upon said sheet material, said pressure means being disposed between said two suction means, and means for driving said suction means operative to first move said first suction means upwardly to partially lift up said pressure means by the sucked sheet material and then upwardly move said second suction means.

The above and other objects, features and advantages of the present invention will be made apparent by the following description with reference to the accompanying drawings, in which:

FIGS. 1 to 3 diagrammatically illustrate heretofore known methods of sucking up and peeling sheet materials one after another from a stack of the sheet materials;

FIGS. 4 to 6 diagrammatically illustrate the method of sucking up and peeling sheet materials one after another from a stack of the sheet materials according to the present invention; and

FIGS. 7 and 8 are schematic views of an embodiment of the apparatus for sucking up and peeling sheet materials one after another from a stack of the sheet materials according to the present invention.

Before the present invention is described with reference to FIGS. 4 to 8 of the drawings, the prior art will be discussed with reference to FIGS. 1 to 3.

With a heretofore known method of sucking up and peeling sheet material one after another from a stack 1 of the sheet materials shown in FIG. 1, suction means 11 and 11a are operated to suck the uppermost one 1a of the stack of sheet materials at substantially the central portions of the left and right sections sectionalized by a center line 4. Simultaneously, the suction means 11 and 11a are lifted together with the sucked sheet material la by means of a support structure 10. At this time, the central portion of the sucked sheet material goes up first so that a partially vacuumed space 5 is formed under the central area of the uppermost sheet material la. Hanged ends 2 and 3 at the opposite sides of the sucked sheet material 1a substantially block the natural supply of air into the space 5. This tends to disadvantageously cause a second sheet material lb to be lifted up together with the uppermost one la.

In an attempt to eliminate the disadvantage, retaining rods 6 are used, as shown in FIG. 2, to hold down the stack 1 at its end portions until the uppermost sheet material, which is sucked by the suction means 11 and 11a at the portions inwardly of the retaining rods 6, is completely separated off the second sheet material lb. In this case, the uppermost sheet material when lifted up has sliding movement with respect to the second sheet material lb so that both sheet materials may be scratched.

if the suction means 11 and lla are operated to suck the opposite ends of the uppermost sheet material la and, at the same time, moved upwardly, asshown in FIG. 3, the ends of the sheet material 1a are first lifted up to cause a relatively good natural air supply inwardly of the opposite ends of the sheet as indicated by arrows, with a result that the tendency that the second sheet material lb is also lifted upwardly is reduced. However, if the sucking means are moved upwardly at a higher speed, the natural air supply is insufficient to prevent the second sheet material lb from being lifted together with the uppermost sheet material. Thus, it is difficult to carry out the operation at a rate greater than a certain rate. In order to eliminate the diffuculty, therefore, a procedure is employed that the air supply is relied upon not only natural air supply but also jets of compressed air or the like so as to ensure that the uppermost sheet material 1a only is lifted up. This procedure, however, needs an additional installation for the air jet. Moreover, there may be a case where the uppermost 1a and the second sheet materials 1b are adhered together by virtue of electrostatic force etc. In such a case, air jet is insufficient to assure complete separation of the uppermost sheet material l'a from the second one lb.

The method of sucking up and peeling sheet materials one after another from a stack of the sheet material according to the present invention will be described with reference to FIGS. 4 to 6. A suction means 11 is disposed above one end 2 of a stack 1 of sheet materials. Another suction means 11a is disposed above the intermediate portion between the other end 3 of the stack 1 and center line 4 thereof. A pressure means 18 is provided at intermediate portion between the suction means 11 and 11a. The pressure means 18 and the suction means 11 and 11a are operable by an upper support structure so as to be moved up and down in a predetermined timed relationship.

In the first position shown in FIG. 4, the suction means 11 and 11a are operated to suck the uppermost sheet material 1a while the pressure means 18 is forced down against the stack 1 with a constant pressure.

In the second position shown in FIG. 5, the right hand suction means 11a positioned between the end 3 of the stack 1 and the center line 4 thereof is maintained in its lower position, whereas the suction means 11 adjacent the other end 2 of the stack 1 is moved upwardly with the pressure means 18 being forced down against the uppermost sheet material 1a with substantially the same pressure force as in the position of FIG. 4. Air is naturally supplied inwardly as shown by an arrow. There takes place little case where the second sheet material lb is lifted up together with the uppermost sheet material la. Of course, if the sucking up and lifting operation is continuously carried out at a high speed, there occurs a case wherein the natural air supply is insufficient to insure that the second sheet material lb is prevented from being lifted up together with the uppermost sheet material. However, since the pressure means 18 holds down the second sheet material lb to cause the same to have a resistance against deformation, it is almost assured that, the second sheet material lb is separated from the uppermost sheet material. In addition, even if the uppermost and the second sheet materials la and lb are adhered to each other by electrostatic force etc., it is almost assured that the second sheet material lb is separated from the uppermost one la by the resistance against deformation.

The left hand suction means 11 is further moved upwardly with the right hand suction means 11a being maintained in its lower position to hold down the uppermost sheet material la. The pressure means 18 is moved upwardly due to the moving up of the left hand suction means 11, as shown in FIG. 6, to such a level as to cause the uppermost sheet material to be arcuately bent upwardly at its left end portion. Thus, even if the second sheet material lb tends to be lifted up together with the uppermost sheet material 1a, the increase in the resistance of the second sheet material lb against deformation and the lapse of time in the process from the position shown in FIG. 5 to that shown in FIG. 6 ensure sufficient natural air supply to cause the end of the second sheet material to be completely separated from the end 2 of the uppermost sheet material. In addition, even if the uppermost and the second sheet materials la and lb are maintained in not completely separated position as shown in FIG. 5 by electrostatic force etc., the increase in the resistance against deformation ensures complete separation of the second sheet material from the uppermost one in the position shown in FIG. 6.

Then, the right hand suction means 11a is moved up to support the sheet material 1a by both suction means 11 and 11a. The upper support structure 10 is laterally moved to a predetermined place in which the suction force is removed from the suction means 11 and 11a to allow the sheet material 1a to drop.

As described above, the uppermost sheet material la is lifted in such a manner that one end thereof is turned up to improve natural air supply. This is combined with the utilization of the resistance of the second sheet material lb against deformation to ensure complete separation of the uppermost sheet material la from the second one lb so that the second sheet material lb is prevented from otherwise being scratched and that the uppermost sheet material la only is positively lifted up.

A description will be made with respect to the apparatus for performing the above-described method by referring to FIGS. 7 and 8. The apparatus includes a support structure 10 which is movable upwardly and downwardly to peeling off and lifting up a sheet material from a stack of sheet materials 1 and which is also movable to convey or transfer the lifted sheet material. The support structure 10 is provided with at least a pair of suction means 11 and 11a and a pressure means 18. The first suction means 11 shown at the left hand por' tion in FIGS. 7 and 8 is supported, from the support structure 10 above the left end portion 2 of the stack of the sheet materials 1 while the second suction means 11a shown at the right hand portion in FIGS. 7 and 8 is supported from the support structure 10 above the intermediate area of the stack between the right end 3 and the central area 4 of the stack. The pressure means 18 is mounted on the support structure between both suction means 11 and 11a. The suction means 11 and 1 la comprise hollow support tubes 12, 12a and suction members 13, 13a mounted on the bottom ends thereof, respectively. The hollow support tubes 12 and 12a vertically slidably extend through vertically elongated guide tubes 14 and 14a, respectively, and are guided by guide members 15 and 15a disposed within the guide tubes. The hollow support tube 12 of the first suction means 11 is somewhat shorter than the hollow support tube 12a of the second suction means 11a, as seen in FIG. 7. The hollow support tubes 12 and 12a have stop plates 16 and 16a secured to the upper end portions of the support tubes, respectively. Preferably, tension springs 17 and 17a are provided to extend between the stop plates 16, 16a and the support structure 10, respectively.

The pressure means 18 provided between the first and second suction means 11 and 11a comprises a tubular member 19 fixedly secured to the support structure 10, a spring 20mounted in the tubular member under compression and a pressure member 21 biased downwardly by the compression spring 20. The pressure member 21 has a downwardly directed shoulder 22 adapted to be engaged by an inner shoulder 23 on the lower end of the tubular member for limiting the downward movement of the pressure member 21.

The stop plates 16 and 16a are fixedly secured to the upper end portions of the hollow support tubes 12 and 12a at such levels that, when the first and second suction members 13 and 13a and the pressure member 21 are in their lifted positions shown in FIG. 8, the first suction member 13 is at a higher level than the other and the line joining the bottom ends of the members 13, 21 and 13a is generally arcuate.

FIG. 8 illustrates the upper support structure in its lifted position wherein a sheet material 1a is shown as being sucked up. The support structure, after having transferred the sheet material 1a to another predetermined place, will be moved downwardly to suck up the next sheet material from the stack. The position of the upper support structure before the downward movement is the same as the position in FIG. 8 in which there is not the sheet material 1a. This position is followed by successive steps of operation which will be described hereunder.

The suction members 13 and 13a are moved downwardly by their hollow support tubes 12 and 12a. The lowermost levels of the suction members 13 and 13a are determined by the engagement of the stop plates 16 and 16a secured to the hollow support tubes 12 and 12a with the top ends of the guide tubes 14 and 14a, respectively. The pressure member 21 is always biased downwardly by the spring 20. The level of the bottom end of the pressure member 21 is determined by the cooperation of the shoulder 22 on the pressure member 21 with the shoulder on the tubular member 19 for guiding the pressure member. In the illustrated embodiment of the invention, the arrangement is such that the suction member 13 of the first suction means 11 is disposed at the highest level and this level is followed by the bottom end of the pressure member 21 and the suc' tion member 13a of the second suction means 11a in the mentioned order and the suction member 13, the bottom end of the pressure member 21 and the suction member 13a are positioned on an arcuate line, as described hereinabove.

From the position described, the upper support structure is moved downwardly so as to suck the stacked sheet materials. The lowermost second suction member 13a is first brought into contact with the uppermost sheet material 1a of the stack and is stopped while the upper support structure still continues its downward movement. This is allowed by the relative sliding movement of the hollow support tube 12a with respect to the guide tube 14a, with a result that the stop plate 16a is spaced from the top of the guide tube 14a.

The continued downward movement of the upper structure 10 then causes the bottom end of the pressure member 21 to contact the top of the stack of sheet material. The support structure further continues its downward movement to bring the first suction member 13 into contact with the top of the stack. The support structure is further moved downwardly an appropriate distance and, thereafter, is stopped. The pressure member 21 is already stopped as described above, but, this does not interfere with the downward movement of the upper support structure 10 as the pressure member 21 has a relative sliding movement with respect to the guide tube 19 in such a manner that the spring 20 is pressed between the pressure member 21 and the guide tube 19. Similarly, the stoppage of the first suction member 13 by contact with top of the stack of sheet materials does not interfere the downward movement of the support structure 10 because the hollow support tube 12 has a relative sliding movement with respect to the guide tube 14.

FIG. 7 illustrates a position in which, after the first suction member 13 has been brought into contact with the sheet material 1a, the support structure 10 has been moved downwardly an appropriate distance and then stopped. In this position, the suction means 13 and 13a will be actuated by any conventional means such as vaccum pump or the like so as to suck the sheet material la. Then, the upper support structure 10 will be moved upwardly to cause the top of the guide tube 14 to abut against the stop plate 16 with a result that the suction member 13 is moved upwardly lifting up the left end portion of the sheet material 1a in the manner and with the advantage previously described with reference to the illustration in FIG. 5.

The support structure 10 is further moved upwardly to cause the shoulder 23 on the guide tube 19 of the pressure member 21 to be cooperated with the shoulder 22 thereon so that the pressure member 21 is moved upwardly together with the support structure 10 in the manner and with the advantage previously discussed in connection with the illustration in FIG. 6.

The upper support structure 10 continues its upward movement to move the suction member 11a upwardly for lifting up the right end of the sheet material 1a, with a result that the sheet material 1a is completely peeled off the second sheet material lb and is lifted up by the suction members 13 and 13a. The upper support structure 10 is further moved upwardly until it is stopped at a predetermined level, as shown in FIG. 8.

Thereafter, the upper support structure 10 will be moved laterally or horizontally to transfer the lifted sheet material 1a toward another predetermined place. When the support structure 10 reaches the other predetermined place, the suction members 13 and 13a will be deenergized to release the sheet material 1a so that the same is released from the suction members 13 and 13a so as to be placed on the pre-determined place.

Then, a description will be made with respect to the functional advantage of the springs 17 and 17a. Since the suction members 13 and 13a are mounted for upward and downward movement by means of the hollow support tubes 12 and 12a, respectively, the springs 17 and 17a are not required by the suction members for their operation for the intended purpose. However, the suction means 11 and 11a would be required to be moved downwardly solely by their gravity if the springs with the top surface of the uppermost sheet material of the stack if the stack has a somewhat corrugated or curved top surface. The springs 17 and 17a assures that the suction members 13 and 13a.are positively moved down and urged into intimate contact with the top surface of the uppermost sheet material la of the stack so that the suction members 13 and 13a, when energized, are operative to suck up the sheet material 1a.

The advantage of the spring for the pressure means 18 will be discussed hereunder. After the sheet material 1a has been sucked by the suction members 13 and 13a, the support structure 10 is moved upwardly to first of all lift up the suction member 13 for turning up the left end of the sheet material 1a, as previously described with reference to FIG. 5. At this time, it is required that the pressure member 21 holds down the sheet material la in order to assure complete separation thereof from the second sheet material 1b until the pressure member is lifted by the upper support structure. In a case where the uppermost sheet material 1a has a great resistance against deformation, there will be a possibility that the pressure member is lifted by the uppermost sheet material due to its resistance against deformation with a resultant decrease in the efficiency of the peeling-off operation. The spring'20 within the guide tube 19 positively enables the pressure member 21 to overcome such resistance against deformation for completelyeliminate the discussed possibility so as to increase the efficiency of the peeling-off operation.

Although the present invention has been described with reference to the illustrated embodiment, it is to be understood that the invention is not limited to the illustrated embodiment and the apparatus of the invention may have any other form that is operative to turn up one end of the uppermost sheet material of a stack of sheet material from the second sheet material of the stack. For example, the upward and downward movement of the suction members can be obtained from pivotal motion of pivotally mounted levers. This is also true with the case of the pressure member.

In addition, the described embodiment has its suction members 13 and 13a and the bottom end of the pressure member 21 mounted on the support structure so that they are positioned on an arcuate line in order to turn up one ends of successive stacked sheet materials. This arrangement is merely employed as a means to utilize the upward .movement of single upper support structure 10 and is not required if the three members 13, 13a and 21 are actuated by separate upwardly and downwardly driving sources. Namely, if the procedure is carried out in such a manner that the suction member 13 is first moved upwardly by its own drive source, then the pressure member 21 is moved upwardly by its own drive source and thereafter the suction member 13a is moved upwardly by its own drive source, the procedure results in the same operation and function as those obtainable from the described embodiment.

Preferably, more than three suction members may be used in order to assure that a sucked sheet material is levelled. In such a case, the suction members are positioned such that they are divided into a first group including the first suction member 13 and a second group including the second member 13a. It is most preferred that the first group includes more than one suction members disposed along one end 2 of the stack of the sheet material 1 so as to turn up successive sheet materials at this end. The limitation to the second group of suction members is not so severe as the limitation to the first group but it is preferred that the second group includes more than one suction members disposed in an appropriate area between the center line 4 of the stack of sheet materials 1 and the end 3 of the stack.

The invention is not limited to the use of a single pressure means and a plurality of such pressure means may be used.

Moreover, the stacked sheet materials have been described and illustrated as being turned up at their left ends. The arrangement of the described and illustrated components of the apparatus, however, may be so modified that the sheet materials are turned up at their right-ends.

Since the apparatus of the present invention is based on the described principle, the apparatus does not require any cooperable installation and is operative to peel off and lift up only an uppermost sheet material in such a manner that the apparatus does not cause any defect such as scratch in the sheet materials. The apparatus is also capable of transferring the lifted sheet material to another predetermined place. Thus, the apparatus is suited for use with an automatic sheet feeding apparatus.

What is claimed is:

1. An apparatus for sucking up the uppermost one of a plurality of stacked sheet materials comprising at least first and second suction means each provided at the lower end thereof with a suction member, said first suction means being disposed above one end of the stacked sheet materials while said second suction means is disposed above the intermediate portion between the other end of the stacked sheet materials and the central portion of the stack, at least one pressure means for applying pressure upon said sheet material, said pressure means being disposed between said two suction means, and means for driving said suction means operative to first move said first suction means upwardly to partially lift up said pressure means by the sucked sheet material and then upwardly move said second suction means, wherein each of said suction means comprises a shaft provided at its bottom end with said suction member, said shaft being slidably extended through guide means secured to an upwardly and downwardly movable support structure and having a stop member secured to the upper end portion thereof, the shaft of said first suction means having a length smaller than that of the shaft of said second suction means.

2. An apparatus as defined in claim 1, wherein said pressure means is positioned between said first and second suction means and is supported from said support structure, said pressure means having a projection always biased downwardly by a spring, said projection having its bottom end positioned at a level lower than the suction member of said first suction means and higher than the suction member of said second suction means when said support structure is in its lifted position.

3. An apparatus as defined in claim 1, wherein a tension spring extends between each stop member and said support structure. 

1. An apparatus for sucking up the uppermost one of a plurality of stacked sheet materials comprising at least first and second suction means each provided at the lower end thereof with a suction member, said first suction means being disposed above one end of the stacked sheet materials while said second suction means is disposed above the intermediate portion between the other end of the stacked sheet materials and the central portion of the stack, at least one pressure means for applying pressure upon said sheet material, said pressure means being disposed between said two suction means, and means for driving said suction means operative to first move said first suction means upwardly to partially lift up said pressure means by the sucked sheet material and then upwardly move said second suction means, wherein each of said suction means comprises a shaft provided at its bottom end with said suction member, said shaft being slidably extended through guide means secured to an upwardly and downwardly movable support structure and having a stop member secured to the upper end portion thereof, the shaft of said first suction means having a length smaller than that of the shaft of said second suction means.
 2. An apparatus as defined in claim 1, wherein said pressure means is positioned between said first and second suction means and is supported from said support structure, said pressure means having a projection always biased downwardly by a spring, said projection having its bottom end positioned at a level lower than the suction member of said first suction means and higher than the suction member of said second suction means when said support structure is in its lifted position.
 3. An apparatus as defined in claim 1, wherein a tension spring extends between each stop member and said support structure. 